The invention relates to a rotor for an electric rotating machine, in particular a synchronous machine, comprising a shaft which can rotate about a rotation axis, and at least one pole shoe.
Furthermore, the invention relates to an electric rotating machine, in particular a synchronous machine, with such a rotor.
The invention further relates to a method for producing such a rotor.
Such a rotor is used, in particular, with direct-starting synchronous salient-pole machines with attached pole shoes. Attached pole shoes occur essentially in large-scale drives with a power output of at least 1 Megawatt.
A direct drive is occasionally an economical method for realizing a start-up on a network, wherein the synchronous machine is started up asynchronously and is put into synchronous operation close to the synchronous rotary speed. For an asynchronous start-up, the rotor must be configured so that the currents needed for the start-up can flow, wherein rotors with solid poles can use the conductivity of the pole surface.
In the case of the asynchronous start-up of a synchronous salient-pole machine, eddy currents are induced in the attached pole shoes, wherein in particular the surface of the pole shoes is severely heated by alternating magnetic fields, particularly due to eddy currents. In the case of large synchronous machines with a power output of at least 1 Megawatt, it is also required that they can start up under a defined countermoment. In the case of such a countermoment, temperatures of several hundred degrees Celsius can arise at the surfaces of the pole shoes.
Evoked by a high temperature difference between a pole shoe and a pole shank, large shear forces can occur at a parting line between the pole shoe and the pole shank. Such a great temperature difference between an underside and an upper side of the pole shoe leads to a deformation, in particular a bowing of the pole shoe. Since the deformation is caused by temperature differences brought about by alternating electromagnetic fields or eddy currents, this is known as an electromagnetically induced thermal deformation. By means of this type of electromagnetically induced thermal deformation, the pole shoe and the pole shank can move relative to one another. The mass displacement of the pole shoe associated with the deformation and displacement have a negative effect on the momentum status of the rotor and thus on the oscillation behavior.
The patent document U.S. Pat. No. 5,949,172 A discloses a motor with a driving coil which is wound round a salient pole. An opening width of an armature core is kept sufficiently large in order to be able to wind the driving coil properly and easily. Following the winding of the driving coil, a magnetic flux collecting plate is mounted on an outer peripheral surface of an arc-shaped region of the salient pole. During the assembly process, two claw-shaped positioning grip portions formed in the magnetic flux collecting plate are fitted into grooves (119) which are each arranged in the upper and lower end faces of the armature core.
The published application JP S59 59033 A discloses a pole for a salient pole rotor, wherein a coil is wound onto a pole body of the pole, which stands out in one piece from a rotary shaft. A pole shoe is fastened onto the pole body with a bolt in order to carry the coil, wherein the head of the bolt is sunk into a bore of the pole shoe. In order to eliminate local temperature increases, the opening of the bore of the pole shoe is closed with a magnetic plate which is configured substantially smooth like the surface of the pole shoe.
The published application DE 21 16 821 A1 discloses a solid pole of an electric motor which starts in an asynchronous region, which has at least one closed cooling circuit of which at least a part is situated in a peripheral pole region and another part is situated in a region of a pole foot. The cooling circuit contains a heat transporting fluid which forms a natural circulating flow during the start-up of the motor under the effect of influencing variables such as acceleration, speed and heating.